Microjet-Based Active Flow Control on a Fixed Wing UAV

Phil Kreth, Farrukh Alvi

Florida Center for Advanced Aero-Propulsion, Florida A & M University and Florida State University, Tallahassee, FL, USA.

DOI: 10.4236/jfcmv.2014.22006                

Abstract

A fixed wing, remote controlled, unmanned aerial vehicle (UAV), has been retrofitted with a system of microjet-based actuators to test microjet efficacy for flow control during flight. This allows one to evaluate the flow control system in a more complex and uncontrolled environment relative to the “clean” laboratory flowfield. The system is composed of off-the-shelf components and provides some appreciation of the challenges associated with implementing such an active control scheme in more “practical” configurations. A wing section with actuators was first tested in a low-speed wind tunnel to characterize microjet control efficacy in the laboratory using surface flow visualizations and particle image velocimetry (PIV). The laboratory results show that the microjet actuators are an effective means of controlling separation with fairly low supply pressures and flow rates. Only relatively robust and straightforward diagnostics can be used to determine the flow conditions on the UAV during flight. As such, tufts are installed on the aircraft’s wing to serve as a qualitative way of measuring control efficacy. Results from the flight tests confirm that this flow control system is capable of delaying flow separation in the complex flows occurring during flight.

Keywords

Separation Control, Unmanned Aerial Vehicle, Flight Testing

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	Lin, J.C. (2002) Review of Research on Low-Profile Vortex Generators to Control Boundary-Layer Separation. Progress in Aerospace Sciences, 38, 389-420. http://dx.doi.org/10.1016/S0376-0421(02)00010-6
[2]	Sinha, S.K. (2001) Flow Separation Control with Microflexural Wall Vibrations. Journal of Aircraft, 38, 496-503. http://dx.doi.org/10.2514/2.2789
[3]	Hsiao, F.-B., Shyu, J.-Y. and Liu, C.-F. (1990) Control of Wall-Separated Flow by Internal Acoustic Excitation. AIAA Journal, 28, 1440-1446. http://dx.doi.org/10.2514/3.25236
[4]	Fujisawa, N. and Takeda, G. (2003) Flow Control around a Circular Cylinder by Internal Acoustic Excitation. Journal of Fluids and Structures, 17, 903-913. http://dx.doi.org/10.1016/S0889-9746(03)00043-4
[5]	Lorber, P.F., McCormick, D.C., Anderson, T.J., Wake, B.E., MacMartin, D.G., Pollack, M.J., Corke, T.C. and Breuer, K. (2000) Rotorcraft Retreating Blade Stall Control. Fluids 2000 Conference and Exhibit, Denver, 19-22 June 2000, AIAA 2000-2475. http://dx.doi.org/10.2514/6.2000-2475
[6]	Pinier, J.T., Ausseur, J.M., Glauser, M.N. and Higuchi, H. (2007) Proportional Closed-Loop Feedback Control of Flow Separation. AIAA Journal, 45, 181-190. http://dx.doi.org/10.2514/1.23465
[7]	Ciuryla, M., Liu, Y., Farnsworth, J., Kwan, C. and Amitay, M. (2007) Flight Control Using Synthetic Jets on a Cessna 182 Model. Journal of Aircraft, 44, 642-653. http://dx.doi.org/10.2514/1.24961
[8]	Seifert, A., Darabi, A. and Wygnanski, I. (1996) Delay of Airfoil Stall by Periodic Excitation. Journal of Aircraft, 33, 691-698. http://dx.doi.org/10.2514/3.47003
[9]	Allan, B.G., Juang, J.-N., Raney, D.L., Seifert, A., Pack, L.G. and Brown, D.E. (2000) Closed-Loop Separation Control using Oscillatory Flow Excitation. NASA/CR-2000-210324, National Aeronautics and Space Administration, Pasadena.
[10]	Beahn, J. (2003) Compressible Dynamic Stall Control Using Microjets. M.S. Dissertation, Florida State University, Tallahassee.
[11]	Bourgois, S., Alvi, F.S., Tensi, J. and Bonnet, J.-P. (2004) Control of Flow Separation Using Microjets. Proceedings of the First European Forum on Flow Control, Poitiers, 11-14 October 2004.
[12]	Fernandez, E., Kumar, R. and Alvi, F. (2013) Separation Control on a Low-Pressure Turbine Blade Using Microjets. Journal of Propulsion and Power, 29, 867-881. http://dx.doi.org/10.2514/1.B34413
[13]	Kreth, P., Alvi, F.S., Kumar, V. and Kumar, R. (2010) Microjet Based Active Flow Control on a Fixed Wing UAV. Proceedings of the 48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition, Orlando, 4-7 January 2010, AIAA 2010-1260. http://dx.doi.org/10.2514/6.2010-1260
[14]	Kumar, V. and Alvi, F.S. (2006) Use of High-Speed Microjets for Active Separation Control in Diffusers. AIAA Journal, 44, 273-281. http://dx.doi.org/10.2514/1.8552
[15]	Kumar, V. (2008) Separation Control in Adverse Pressure Gradients using High-Speed Microjets,. Ph.D. Thesis, Florida State University, Tallahassee.
[16]	Kumar, V. and Alvi, F.S. (2009) Toward Understanding and Optimizing Separation Control using Microjets. AIAA Journal, 47, 2544-2557. http://dx.doi.org/10.2514/1.38868
[17]	Muppidi, S. and Mahesh, K. (2007) Direct Numerical Simulation of Round Turbulent Jets in Crossflow. Journal of Fluid Mechanics, 574, 59-84. http://dx.doi.org/10.1017/S0022112006004034
[18]	Kähler, C., Sammler, B. and Kompenhans, J. (2002) Generation and Control of Tracer Particles for Optical Flow Investigations in Air. Experiments in Fluids, 33, 736-724. http://dx.doi.org/10.1007/s00348-002-0492-x?